Typical forage harvesters usually embody a portable vehicle adapted to travel down rows of field borne crops. Such devices are equipped with a header attachment for delivering incoming forage to a suitable processing mechanism, which in the case of an ensilage harvester, will comprise suitable chopping and blowing means. The header attachment positioned in front of the processing mechanism, includes means for severing the forage and means for conveying the severed forage to the processing mechanism. Generally, header attachments include a pair of laterally opposed, endless conveyor belts defining between them a forage material receiving passage; the belts are adapted to grip forage and move it through the passage to the processing mechanism. Typically, header attachments also include a conventional oscillating cutting knife or sickle bar for severing the forage material from the field.
The reciprocating sickle employed to sever forage stalks has presented problems in conventional row crop header attachments. A reciprocating sickle is difficult to balance out, in part because of the varying loads imposed upon it. Uneven loading is caused by differences in the size of stalks and differences in resistance to cutting caused by varying condition, such as moisture content and density, of the crop material. In addition, the sickle must change direction twice during each cycle. This involves stopping and starting twice during each cycle to change direction. For these reasons, a reciprocating or oscillating sickle can seldom be completely balanced out. The difficulty in balancing out reciprocating sickles is evidenced by vast numbers of models used, and the frequent modification made to reduce vibration.
Rotary cutters have been employed with row crop header devices for forage harvesters. Desirably, a forward idler wheel for the endless belt conveyor of the header supports and drives the rotating cutter blades which cooperate with a fixed cutter blade. While the use of a rotary cutter obviates problems presented by the use of an oscillating sickle cutter, other problems are presented. To maintain proper tension on the conveyor belt, it is desirable that the forward idler be adjustable. Adjustment of a forward idler, carrying and driving a rotating cutter blade, can adversely affect the relative orientation of the rotating blade and the fixed cutter blade.
In addition to the problems with the severing means, the conveying means of conventional row crop header devices are not as efficient as desirable. Typically, such conveying means involves the use of two cooperating belts composed of steel chain links equipped with crop material engaging lugs. Such chains inefficiently feed the processing mechanism, often become wrapped with the crop material, have a short life, and are noisy during operation. In addition, the design of many current conveying means have little flexibility and do not readily adapt to differences in crop particle size. Oversized material passing through the conveying means can readily choke and jam the mechanism. Excess bulk can also stress components, such as the conveyor frame structure, resulting in misalignment of the cooperating conveyor belts or in breakage of the device.
The row crop harvesting device of the present invention preferably employs a rotary cutter cooperating with a second cutter element. The rotary cutter is supported and driven by a forward idler of the conveying means, which forward idler may be adjusted without affecting the cutting relationship of the rotary cutter and the second cutter element. The conveying means of the row crop harvesting device of the present invention provides for conveying crop material of different sizes without choking or excessively stressing various components. In addition, the design of the row crop harvester of the present invention inherently provides simplicity, ease of maintenance, quiet operation and sturdy construction.